JSFiddle - React, Tailwind, and code Playground

HTML

<select class="bus-width btn-light-outline">
    <option value="No Path">No Path</option>
    <option value="Mono">Mono</option>
    <option value="Stereo">Stereo</option>
    <option value="Surround">5.1 Surround</option>
  </select>


<div class="do-something">This needs to be triggered</div>

CSS

.do-something {
    position:absolute;
    bottom:70px;
    padding:30px;
    background:white;
    border:1px solid black;
}
.triggered {
  background:green;  
}

JavaScript

var lastIndex = null;

$('select').on('change', function () {
    
    var thisIndex = $(this).find(":selected").index();
    
    if(thisIndex < lastIndex){
        $('.do-something').addClass('triggered');   
    } else {
        $('.do-something').removeClass('triggered');   
    }
    
    lastIndex = thisIndex;
    
});